Idle Air Control Valve

BAC VALVE
- Connect the SST (System Selector) to the data link connector.
- Set switch A to position 1.
- Set the test switch to SELF TEST.
- Connect the SSTs (NGS) to the data link connector-2.





- Select the PID/DATA MONITOR AND RECORD function.
- Verify that the engine is cold condition, and start the engine.
- Select the "RPM" on the NGS display.
- Verify that the engine speed decreases as the engine warms up.





- Disconnect the SST (System Selector).
- If the engine speed will not decrease or decreases slowly, check the water hose connected to BAC valve for leakage and clogs.
- If the water hose is OK, inspect the following.
- Air valve
- IAC valve

IDLE AIR CONTROL VALVE
- Start the engine and run it at idle.





- Disconnect the IAC valve connector and verify that the engine speed changes.
- If the engine condition will not change, do as follows.
- Connect the SSTs (NGS) to the data link connector-2.
- Verify that diagnostic trouble code No. P0505 is not displayed. If code No. P0505 is shown, carry out troubleshooting of the code No. P0505.





- Select the SIMULATION TEST function on the NGS display.
- Change the duty value of the IAC valve to 100% by using the "IACV" and verify that the idle speed increases.
- If the idle speed increases, replace the ECM.
- If the idle speed does not change. Replace the IAC valve.
- Warm up the engine to normal operating temperature and run it at idle.
- Turn the electrical loads ON and verify that the engine speed is with in the specification.




ENGINE SPEED (RPM)

NOTE: Excludes temporary idle speed drop just after the electrical loads are turned ON.

- If not as specified with all load condition, inspect the idle air control valve. If not as specified with each load condition, check related input switches, harnesses and connectors.